Multilayer hollow fiber wound body

ABSTRACT

A multilayer hollow fiber wound body, in which at least a portion of the hollow fibers is formed as helices and/or a portion of the hollow fibers as spirals. The hollow fibers within each hollow fiber ply are disposed at regular intervals to each other. The hollow fibers of adjacent, successive hollow fiber plies cross. The hollow fibers are disposed in the form of at least two superposed and then spirally wound hollow fiber mats, the hollow fibers within each hollow fiber mat being held by several inserted transverse fibers or the like. Within each hollow fiber mat the regular interval between the transverse fibers or the like is greater than the regular interval between the hollow fibers, and none of the hollow fibers has a deflection site, whereby according to the invention the ratio of the regular interval between adjacent transverse fibers within each hollow fiber mat to the regular interval between adjacent hollow fibers within each hollow fiber mat falls in the range of 2 to 40.

TECHNICAL FIELD

The invention relates to a multilayer hollow fiber wound body, in whichat least one portion of the hollow fiber is formed as helices and/or aportion of the hollow fibers as spirals. The hollow fibers within eachhollow fiber ply are disposed at regular intervals to each other. Thehollow fibers of adjacent, successive hollow fiber plies cross. Thehollow fibers are disposed in the form of at least two superposed andthen spirally wound hollow fiber mats. The hollow fibers within eachhollow fiber mat are held by several inserted transverse fibers or thelike. Within each hollow fiber mat the regular interval between thetransverse fibers or the like is greater than the regular intervalbetween the hollow fibers, and none of the hollow fibers has adeflection site. The invention also relates to a process for theproduction of the hollow fiber wound body, as well as to the use of thehollow fiber wound body.

BACKGROUND

Hollow fiber wound bodies are known, which are produced by the windingof a hollow fiber onto a spool. This type of production is very costlyand offers only limited design options for the hollow fiber wound bodiesthat can be produced in this manner.

Multilayer hollow fiber wound bodies made of a spirally wound wovenmaterial or knitted material, made of hollow fibers, are also known. Inthis type of hollow fiber wound bodies, kinking of the hollow fibers atcrossing points can occur. In addition, the production of woven andknitted materials from hollow fibers is costly.

A multilayer hollow fiber wound body is known from European Patent EPNo. 81 0,093,677; the disclosed body can be produced by rolling upseveral layers of superposed, mutually crossing hollow fibers into aspiral form. The individual hollow fiber layers of this wound body arethus subsequently disposed in a spiral form, whereby the hollow fibersare not held by several transverse fibers. Because of the resultingabsence of adequate cross mixing, convective heat or mass transport intothe extra-capillary compartment in this known hollow fiber wound bodyleaves much to be desired. In addition, it appeared in practice that theoriginally regular arrangement of the hollow fibers is greatly disruptedby further processing, so that gaps form, which result in channeling,because of shifting and juxtaposing of hollow fibers. The disclosedproduction process is moreover very costly and offers only limiteddesign options for the hollow fiber wound body. In addition, some hollowfibers in these hollow fiber wound bodies have deflection sites, whicharise at the cylinder end because of the reversal of the traversingmovement during the wrapping of the polygonal cylinder with hollowfibers. The hollow fibers can be damaged at the deflection sites by thismeans, i.e., become loose or even break.

A hollow fiber wound body is known from Unexamined West German PatentApplication (DE-OS) No. 2,300,312, in which a plurality of layers ofhollow fibers are disposed over one another on a core, whereby mutuallyadjacent hollow fibers proceed essentially parallel to each other withineach individual layer, whereas adjacent hollow fibers of adjacent,successive hollow fiber layers cross at an angle in each case.Production proceeds by the winding of a hollow fiber also over the endsof a core in several layers, thus not by spiral winding of a hollowfiber fabric. This type of production of a hollow fiber wound body isvery costly and results in a high proportion of waste, because thehollow fiber segments wound on the ends of the core must be discarded.Moreover, the absence of transverse fibers or the like not only producesinadequate cross mixing in the extra-capillary compartment, but also avery irregular structure of the hollow fiber wound body, because thegenerally very smooth hollow fibers slip out of place even during theproduction of the hollow fiber wound body, which leads to thejuxtaposing of very many hollow fibers or hollow fiber sections; on theone hand, this results in channeling, and on the other, in the coveringof a large portion of the surface effective in heat or mass transfer.

A hollow fiber membrane apparatus is known from East German Patent(DD-PS) No. 233,946; the apparatus is produced by preparation of webs ofparallel hollow fibers, preferably by sewing, winding of the webs into afiber bundle, and formation of connections. The fiber bundle is wound upof at least two webs, whereby the hollow fibers of adjacent webs aremutually disposed at an angle of 10° to 80°; this is preferably achievedin that the webs are obliquely deformed outward from the edges. Thelateral interval between seams is thereby relatively large, so that inthis known hollow fiber membrane apparatus as well, adjacent hollowfibers touch each other after the webs are wound into a fiber bundle;this leads to channeling and the covering of the membrane surface andconsequently to deterioration in heat and/or mass transfer.

SUMMARY OF THE INVENTION

The present invention has as an object the provision of a multilayerhollow fiber wound body of the aforementioned type, the hollow fibers ofwhich are disposed at a regular lateral interval along the entire lengthand which for this reason assures improved convective heat and/or masstransport and increased heat and/or mass transfer, and which offers morecombination and design options relative to the arrangement of hollowfibers and can be produced in a simple manner.

It has now been found that only when the ratio of the regular lateralinterval between adjacent transverse fibers within each hollow fiber matto the regular lateral interval between adjacent hollow fibers withineach hollow fiber mat falls within a certain range, a juxtaposing ofadjacent hollow fibers is avoided with certainty. The intersticesbetween adjacent transverse fibers and adjacent hollow fibers, in thiscase, are sufficiently large to ensure good perfusion of the hollowfiber wound body with a suitably low pressure loss. As is generallyknown, hollow fibers, which were wound into a bobbin before beingprocessed into a hollow fiber mat, can be formed as waves. Such hollowfibers have an especially great tendency for mutual contact, if they areprocessed into a hollow fiber mat and the lateral distance of transversefibers is too large. This circumstance was apparently not considered todate, for which reason the regular lateral interval between transversefibers in known hollow fiber wound bodies made of such mats was selectedto be relatively large.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described more extensively with reference to thefigures, in which

FIG. 1 shows an embodiment of the hollow fiber wound body in section;

FIGS. 2 to 4 show designs for the hollow fiber wound body;

FIG. 5 shows a cross section of the hollow fiber wound body of FIG. 4.

FIG. 6 shows a special hollow fiber configuration;

FIG. 7 shows in a simplified schematic diagram, a preferred embodimentof the process for producing the hollow fiber wound body;

FIG. 8 shows in a simplified schematic diagram, another embodiment ofthe process for producing the hollow fiber wound body;

FIG. 9 shows different designs for hollow fiber mats suitable forproducing the hollow fiber wound body;

FIG. 10 shows a device with an embodiment of the hollow fiber woundbody; and

FIG. 11 explains the measuring of the novel range.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The lateral interval between adjacent hollow fibers within each hollowfiber mat in terms of the present invention is understood to be theinterval in the immediate region of the transverse fibers, because it isessentially established in this region.

The regular lateral interval between adjacent transverse fibers oradjacent hollow fibers need not be identical within a hollow fiber mat,as long as each interval ratio falls within the novel range. Likewisethe regular intervals between adjacent transverse fibers or hollowfibers of the different hollow fiber mats forming the hollow fiber woundbody need not be identical, thus equivalent to each other.

To determine the interval ratio, the lateral intervals between adjacenttransverse fibers and adjacent hollow fibers are determined in the samesegment of the hollow fiber mat. The transverse fibers and hollowfibers, used in measuring the interval ratio, essentially form arectangle or parallelogram and the lateral intervals between transversefibers or hollow fibers correspond to the intervals between the oppositesides of the rectangle or parallelograms formed by them.

The novel hollow fiber wound body is suitable for the treatment ofliquid, vaporous, and gaseous media.

The novel hollow fiber wound body can have a cross section filled withhollow fibers or a ring-shaped cross section with a central axialperfusion channel or a ring-shaped cross section with a core filling thecentral axial cavity. In this case, this can refer to a solid core,which totally fills the central axial cavity, or to a tubular coreforming the central axial perfusion channel. The hollow fiber wound bodycan also be formed to be flat in cross section. This type of flat hollowfiber wound body is obtained, for example, by winding hollow fiber matsonto a core with a flat shape (plate). The cross section of the core inso doing preferably has the form of a rectangle with rounded corners, asegment of a circle or semi-circle with rounded edges, a lens, anellipse or a sickle with rounded edges. These types of core shapesproduce space-saving hollow fiber wound bodies or those that are betteradapted, for example, to the body surface of a patient. For the tubulardesign of the core, whereby this can also have one of the aforementionedcross-sectional forms, the wall (sheath) of the core can also havebreaks to enable, for example, radial perfusion of the hollow fiberwound body.

Helical in terms of the present invention is defined as "the form of asteep helix in relation to the longitudinal axis of the fiber woundbody, thus the form of a helix with a large helix angle." This has theeffect that the length of hollow fibers thus formed is essentially notgreater than the length of the hollow fiber wound body.

Spiral in terms of the present invention is defined as "the form of aspiral arranged in a plane lying essentially perpendicular to thelongitudinal axis of the fiber wound body." This has the effect thatdepending on the number of the hollow fiber plies and the hollow fiberlayers and depending on the length of the hollow fiber wound body, thespiral hollow fibers can also have a length that is essentiallydifferent from the length of the hollow fiber wound body.

The terms hollow fiber ply and hollow fiber mat are defined as follows:hollow fiber mat is a flat, single-layer arrangement of hollow fibers,the said mat in which the hollow fibers are held by fiber-shaped orband-shaped or similarly formed means proceeding obliquely relative tothe hollow fibers. A hollow fiber ply is defined as a fiber mat sectionwound in the production of the hollow fiber wound body per completerevolution of the said body. If, for example, two hollow fiber mats arethus wound on a single core, in that 10 full rotations are permitted,then a hollow fiber wound body is obtained, which has a total of twotimes ten, thus 20, hollow fiber plies.

A hollow fiber layer is defined as a wound hollow fiber mat.

Within a hollow fiber layer or mat, the hollow fibers need notabsolutely be arranged parallel to each other, although, as a rule, thismight be the most feasible design.

The transverse fibers or the like, keeping the hollow fibers at theregular intervals from each other, can, for example, be introduced by aweaving or knitting process thus, for example, as so-called warp orfilling threads. To improve the convective heat or mass transport, thehollow fibers and/or transverse fibers are preferably structured and/orshaped. If, for example, textile multifilament fibers are used, thenthese are preferably textured. The transverse fibers should preferablybe guided rather loosely around the hollow fibers to avoid angularlyinflexible linkage or constriction of the hollow fibers by thetransverse fibers.

The hollow fibers of adjacent successive plies of the hollow fiber woundbody can also be formed as uniformly helical, but they then have avariable length, by virtue of the condition that they cross. Generally,the hollow fibers of adjacent successive plies are helical in oppositedirections or alternately helical and spiral or alternately helical andrectilinear (axially parallel) or alternately spiral and rectilinear.However, three or more layers of variably formed hollow fibers can alsoalternate, i.e., be arranged in successive plies. For example,alternately helical, spiral, and rectilinear hollow fibers oralternately two plies of hollow fibers, which are helical in theopposite direction, and a ply of spiral or rectilinear hollow fibers. Ineach case, however, only those hollow fibers cross that do not belong tothe same hollow fiber layer.

The hollow fiber wound body can have hollow fibers that are suitable forheat transfer and/or hollow fibers that are suitable for mass transfer,mass exchange and/or material separation. Hollow fibers, differingrelative to their properties and/or their dimensions and/or their form,can also be disposed together in a hollow fiber wound body. For example,heat transfer from a medium A to a medium B can be effected by hollowfibers suitable for this, whereas at the same time mass transfer frommedium B to a medium C and/or vice versa can occur with the use ofhollow fibers suitable for this. Microporous hollow fibers can also usedfor mass transfer. The pores of the hollow fibers can be also be filledwith suitable substances for this purpose; the interior of the hollowfibers, i.e., the lumen, can also be filled.

The hollow fibers of the wound body can also differ relative to theirmatter transport properties. For example, they can have differentselectivities or semipermeabilities for different substances, behydrophilic or hydrophobic, be porous or have no pores, etc.

Differences in form, for example, can consist in the fact that in oneportion of the hollow fibers the external contour, thus the outline ofthe hollow fibers, in cross section is formed essentially round orcircular and that in another portion of the hollow fibers the externalcontour in section is triangular, square, three-lobed, four-lobed, etc.

Differences can also exist in hollow fiber diameters and hollow fiberlengths. The hollow fibers can also have differently shaped lumen crosssections and/or wall thicknesses.

The hollow fiber wound body is therefore suitable for the production,for example, of filters, oxygenators, hemofilters, blood plasmaseparators, IV filters, cross-flow microfilters, gas separators,membrane distillation devices, bioreactors, adsorbers, absorbers,desorption agents, dialyzers, exchange columns, packing for packedcolumns, controlled slow release of active substances, odoroussubstances, and the like, etc. For this purpose, the hollow fiber woundbody, as is also known for prior art hollow fiber wound bodies, can beplaced in a suitable housing, which has the necessary connections forsupplying and removing the media involved in heat and/or mass transfer.

The two end regions of the hollow fibers of the novel hollow fiber woundbody can be embedded or introduced into a curable casting material--asis also typical for prior art hollow fiber wound bodies and hollow fiberbundles. Removal of a sufficiently long section of the cured castingmaterial achieves the situation that the hollow fibers with their openends open onto the outer surface of the so-called tube sheet arisingthereby. The hollow fiber wound body thus formed can then be used like afilter cartridge in a housing with connections for fluids. The sealingof the hollow fiber end regions can occur, however, only after thehollow fiber wound body is placed in a housing with connections forfluids, so that the casting material itself effects the fluid-imperviousseal with the housing. This is also known from the state of the art andtherefore does not need to be explained further here.

In flowing around the hollow fibers of the hollow fiber wound body inthe longitudinal direction, the fluid in question is frequently broughtto the end of the hollow fiber wound body generally radially and removedagain radially at its other end, generally on the opposite side. Uniformadmission to all hollow fibers also in the region of the medium supplyis therefore important to avoid channeling within the hollow fiber woundbody. To achieve this, the hollow fibers of the hollow fiber wound bodyare advantageously disposed in groups especially in the region of themedium supply in at least one hollow fiber layer, whereby in this regionthe interval between the hollow fibers within a group is smaller thanthe interval between the outer fibers of the adjacent fiber groups.Preferably, however, the flow proceeds transversely around the hollowfibers--thus essentially perpendicular to their longitudinal axis.

When the hollow fiber wound body with hollow fibers is used, forexample, for gas separation, for blood plasma recovery, forhemofiltration, for dead-end filtration, for deaerating a liquid, or thelike, the hollow fibers of at least one hollow fiber layer can be sealedat one end of the fiber layer.

To even out the flow of a fluid around the hollow fibers of the hollowfiber wound body, a fluid-permeable, more or less stiff or elasticfabric can be disposed between at least one portion of the hollow fiberplies of the hollow fiber wound body.

In addition, the said fabric can be formed so that it removessubstances, present in the fluid flowing around the hollow fibers, byabsorption or adsorption from the fluid. For example, fibers made ofactivated carbon or the like are suitable for this purpose.

For the production of the multilayer hollow fiber wound body accordingto the invention, at least two superposed hollow fiber mats (in whichthe hollow fibers within each hollow fiber mat are disposed at regularintervals to each other and are held by several inserted transversefibers or the like, within each hollow fiber mat the regular intervalbetween the transverse fibers or the like is greater than the regularinterval between the hollow fibers, whereby the ratio of the regularinterval between adjacent transverse fibers within each hollow fiber matto the regular interval between adjacent hollow fibers within eachhollow fiber mat falls in the range of 2 to 40, and none of the hollowfibers has a deflection site) are wound spirally around an axis ofrotation, whereby the hollow fibers of adjacent hollow fiber mats aredisposed in a mutually crossing manner before winding.

To produce the hollow fiber wound body, different hollow fibers can alsobe used, whereby different hollow fibers can be disposed also within atleast one hollow fiber mat. As has already been set forth extensivelyabove, different signifies different relative to their dimensions, theirform, their material, their properties, their function, etc.

At least one fluid-permeable fabric, thus, for example, a nonwovenmaterial, a woven material, a knitted material, a foamed plastic, etc.,can be wound together with the hollow fiber mats.

However, just as many, if necessary also different, fabrics as hollowfiber mats can be wound, so that a ply of fluid-permeable fabric isarranged between each hollow fiber ply in the finished hollow fiberwound body. This can possess adsorptive or absorptive properties asalready set forth above.

The hollow fiber mats can be produced on a loom or a knitting machine,whereby the transverse fibers holding the hollow fibers at regularintervals to each other can be introduced as filling or warp threads.Naturally, it is also possible to use other agents, for example, in theform of a ribbon or tape to hold the hollow fibers. These can also bedisposed as filling or warp threads in a woven or knitted material, oron one side, i.e., only on one side of the hollow fiber mat in eachcase. In addition, these can act as spacers between adjacent hollowfiber layers.

The use of transverse fibers, however, is preferred, because in thiscase the linkage between the inserted transverse fibers and the hollowfibers is relatively loose, i.e., not angularly inflexible, so that therelative position of the hollow fibers and the inserted transversefibers to each other, thus the crossing angle between the two, can beeasily altered. This enables a very advantageous production of thehollow fiber wound body and multiple design options of the body,particularly if the starting material is a hollow fiber mat, in whichthe hollow fibers and the inserted transverse fibers cross essentiallyat right angles and in which the longitudinal axis of each hollow fiberis disposed first essentially perpendicular to the direction oftransport of the hollow fiber mat before winding and parallel to theaxis of the rotation of the hollow fiber wound body, as will bedescribed and explained in greater detail below.

Within the hollow fiber mats, both solid fibers and hollow fibers can bedisposed at regular or irregular intervals from each other, in the eventthis were to be advantageous in the production of hollow fiber mats orthe hollow fiber wound body or the employment thereof. One portion ofsolid fibers, however, can also fulfill merely a purely mechanicalfunction, thus, for example, endow the hollow fiber wound body withgreater form stability.

In producing the hollow fiber wound body, for each layer with hollowfibers to be formed in a helical shape, a hollow fiber mat with hollowfibers arranged parallel to each other can be used as the starting pointin an especially advantageous manner. The longitudinal axis of eachhollow fiber is arranged first essentially perpendicular to thedirection of hollow fiber mat transport before winding. If one side ofthe hollow fiber mat is now passed over a longer distance of thetransport route than the other side of the hollow fiber mat, then thehollow fiber ends on this one side of the hollow fiber mat lag behindthe fibers ends on the other side of the hollow fiber mat. This has theeffect that, relative to their original position, the hollow fibers arebrought into an oblique position, i.e, form an angle, which is greateror smaller than 90°, relative to the direction of transport. If thehollow fibers are brought into an oblique position in this mannerdirectly before winding relative to the axis of rotation of the hollowfiber wound body, so that they also form an angle with the axis ofrotation, then this by necessity produces a helical formation of theaffected hollow fibers in winding of the same, e.g., on a core or on thehollow fiber wound body in the process of being formed. For example,each of these hollow fiber mats can be transported before winding firstin a plane parallel to the axis of rotation of the hollow fiber woundbody, whereby the direction of transport, however, is parallel oroblique, but not perpendicular to the axis of rotation of the hollowfiber wound body. The hollow fiber mat must be deflected for thetransport of the hollow fiber mat to finally proceed perpendicular tothe axis of rotation of the hollow fiber wound body. If, in so doing,the deflection of the hollow fiber mat before winding occurs in the sameplane in such a way that the hollow fiber ends on one side of the hollowfiber mat describe an arc of a circle with a larger radius than thehollow fiber ends on the other side of the hollow fiber mat, then thehollow fiber ends on the larger, i.e., longer, arc of a circle lagbehind the hollow fiber ends on the smaller, i.e., shorter, arc of thecircle, so that the hollow fibers are brought in this way into anoblique position relative to the axis of rotation of the hollow fiberwound body.

An especially preferred production method is to move each of the hollowfiber mats, designated for hollow fibers to be formed helically, firstwith hollow fibers disposed parallel to each other and to the axis ofrotation of the hollow fiber wound body, perpendicular to theirlongitudinal axis and thus longitudinal to the axis of rotation of thehollow fiber wound body in a plane parallel to said axis toward the axisof rotation. If one side of the hollow fiber mat is thereby deflectedshortly before winding essentially perpendicular to the plane, in whichthe hollow fiber mat is being transported, for example, by a deflectionroller, then the transport distance of the hollow fiber ends, which runover the deflection roller, is greater than that of the hollow fiberends on the other side of the hollow fiber mat, which do not leave theplane of transport. This deflection creates the situation in which thedeflected hollow fiber ends lag behind the other hollow fiber ends, sothat the hollow fibers are brought into an oblique position, i.e., intoa nonparallel position, relative to the axis of rotation of the hollowfiber wound body.

In hollow fiber mats with hollow fibers not disposed parallel to eachother, the assumption of a different form by hollow fibers after windingin the hollow fiber wound body can be achieved in this way; thus theycan be formed as helices proceeding in the same direction but differingin the degree of their helical nature, as helices proceeding in the sameand/or opposite direction, and as helices which are rectilinear (axiallyparallel) or proceed in the opposite direction.

The hollow fibers are preferably made of polymers that can be melt spunor regenerated cellulose, whereby the hollow fibers preferably arecomprised of a biocompatible material when the hollow fiber wound bodyis to be used in the medical field.

The transverse fibers or the like or the solid fibers can also be madefrom a polymer or regenerated cellulose, but also, for example,partially or totally of activated carbon. The surface of the hollow,transverse, or solid fibers can also be coated with sorbents.

FIG. 1 shows in a simplified schematic diagram the structure of amultilayer hollow fiber wound body in cross section. In this case, thehollow fiber wound body consists of a total of two spirally wound hollowfiber mats 1a and 1b, whereby, as indicated by lines 1'a and 1'b, thehollow fiber wound body can have any number of hollow fiber plies. Toillustrate the structure of the hollow fiber wound body, hollow fibers1b are depicted as dark circles. Hollow fibers 1a and 1b are arranged atregular intervals to each other within the layer to which they belongand are held by inserted transverse fibers (not shown). Hollow fibers 1aand/or 1b are formed as helices. Hollow fibers 1a or 1b, however, canalso be formed to be rectilinear, thus axially parallel. In each case,hollow fibers 1a cross hollow fibers 1b.

In the embodiment of the hollow fiber wound body as shown in FIG. 2,hollow fibers 1a are helical, whereas hollow fibers 1b are rectilinearand disposed parallel to the axis. Hollow fibers 1a form the anglealpha-a with the longitudinal axis of the hollow fiber wound body.

In the embodiment of the hollow fiber wound body shown in FIG. 3, bothhollow fibers 1a and hollow fibers 1b are helical, however helical inthe opposite direction. Hollow fibers 1a form with the longitudinal axisof the hollow fiber wound body the angle alpha-a, which in terms of thepresent invention is defined as being greater than 0, whereas hollowfibers 1b with the longitudinal axis of the hollow fiber wound body forthe angle alpha-b, which by definition is smaller than 0, in theabsolute sense, but can be equal to angle alpha-a.

In the embodiment of the hollow fiber wound body shown in FIG. 4, hollowfibers 1a are helical and hollow fibers 1b are spiral. The structure ofthe hollow fiber wound body and the design of hollow fibers 1a and 1b inthis embodiment are illustrated in FIG. 5, which shows the hollow fiberwound body in FIG. 4 in cross section. As is illustrated in addition byarrows A, B, and C in FIG. 5, a hollow fiber wound body designed in thismanner can be used to allow three media concurrently to participate in amatter and/or heat exchange. In so doing, medium A flows through thehelical hollow fibers 1a, medium B through the spiral hollow fibers 1b,and medium C around hollow fibers 1a and 1b, whereby its direction offlow proceeds essentially transversely to the longitudinal axis of thehollow fiber wound body.

The inserted transverse fibers or the like are identified by thereference number 2 in the hollow fiber wound bodies shown in FIGS. 2 to5.

In the hollow fiber mat shown in FIG. 6, three hollow fibers 1 in eachcase at the left end of the hollow fiber mat are combined into groups byspecial disposition of the inserted transverse fibers 2 or the like,whereby within each group the interval between hollow fibers 1 issmaller than the interval between the outer hollow fibers of bothadjacent hollow fiber groups depicted. The gap 3, formed by thisdisposition of hollow fiber ends, between the hollow fiber groupspermits better penetration of the medium flowing around the hollowfibers in the hollow fiber wound body. The additional transverse fibers2 or the like, inserted in the middle of hollow fibers 1 are disposedsuch that they hold hollow fibers 1 at a regular, essentially identicalinterval to each other.

An especially preferred embodiment of the process for the production ofthe hollow fiber wound body is shown in FIG. 7. The mode of action ofthe process is illustrated by the sections A--A and B--B, whereby aportion of the hollow fiber ends is identified by a, b, etc., to m, andthe other ends of the relevant hollow fibers 1 by a', b', etc., to m'.The respective position of the hollow fiber ends can be seen both in theplan and also in sections A--A and B--B. For the sake of simplicity,only one hollow fiber mat is shown, which is formed by hollow fibers 1and the inserted transverse fibers 2 or the like and is wound spirallyinto hollow fiber wound body 5, in which hollow fibers 1 are disposedhelically. Hollow fibers 1 are held by the inserted transverse fibers 2or the like at a regular interval to each other. First, hollow fibers 1are aligned parallel to the axis of the rotation, i.e, the longitudinalaxis, of hollow fiber wound body 5, thus perpendicular to the conveyingdirection, indicated by arrow 7, of the hollow fiber mat. The hollowfiber mat in so doing is moved over rollers 3, 4, and 6 at a constantrate onto the axis of rotation of the hollow fiber wound body 5. Whereasthe hollow fiber mat on the side with hollow fiber ends a to messentially experiences no notable deflection on its way to the axis ofrotation of hollow fiber wound body 5, the hollow fiber mat on the sidewith the hollow fiber ends a' to m' is passed over deflection roller 4,whereby the hollow fiber ends a' to m' cover a longer distance than thehollow fiber ends a to m; for this reason the former lag behind, andtherefore are brought into a position that is not parallel relative tothe axis of rotation (longitudinal axis) of hollow fiber wound body 5.As FIG. 7 shows in addition, the width of the hollow fiber mat isslightly reduced by the oblique position of hollow fibers 1.

The previously described operation is facilitated if the linkage betweenhollow fibers 1 and the inserted transverse fibers 2 or the like permitsa change in the relative position to each other without kinking of thehollow fibers at this site, i.e., if this linkage is not angularlyinflexible. This also applies to the process shown in FIG. 8. As can bederived, moreover, from FIG. 7, the oblique position of hollow fibers 1immediately before winding can be varied as desired by the degree ofdeflection with the use of deflection roller 4. In other words, thegreater the deflection, the greater the lag of hollow fiber ends a', b',etc., and the greater the oblique position of hollow fibers 1, i.e., thegreater the angle formed by the hollow fibers 1 with the longitudinalaxis (axis of rotation) of hollow fiber wound body 5. The diagram inFIG. 7 shows in addition that an oblique position of hollow fibers 1,the said position being a mirror image of the depicted oblique positionof hollow fibers 1, can be achieved by placing deflection roller 6 in aposition that corresponds to the depicted position of deflection roller4 and vice versa. Thereby, that side of the hollow fiber mat on whichthe hollow fiber ends a to m are located is deflected, but not the sideon which the hollow fiber ends a' to m' are located, so that the hollowfiber ends a, b, etc., to m experience a lag versus the hollow fiberends a', b', etc. to m'.

To produce a hollow fiber wound body with hollow fibers formed helicallyin opposite directions and disposed in two spirally wound hollow fibermats, one can thus begin, for example, with two hollow fiber mats, thehollow fibers 1 of which are arranged parallel to the axis of rotationof the hollow fiber wound body 5 first as depicted in FIG. 1, and thehollow fibers 1 of which are brought into an oppositely running obliqueposition by the fact that in the one hollow fiber mat the side with thehollow fiber ends a, b, etc., and in the other hollow fiber mat the sidewith the hollow fiber ends a', b', etc., are deflected. It is alsopossible, however, in the depicted example to deflect the two hollowfiber mats on the same side but to differing degrees. This produces thesituation in which the hollow fibers of the hollow fiber mat the side ofwhich is more extensively deflected is brought into a greater obliqueposition than the hollow fibers of the other hollow fiber mat and thehollow fibers of the two hollow fiber mats thus cross and are formedhelically in the same direction in the hollow fiber wound body.

Another embodiment of the process is shown in FIG. 8 in a simplifiedschematic diagram; in the said embodiment, the hollow fiber wound body 5with hollow fibers 1, formed helically in opposite directions anddisposed in two spirally disposed layers, is produced from two hollowfiber mats. Each hollow fiber mat consists of hollow fibers 1 and theinserted transverse fibers 2 or the like. Each hollow fiber mat istransported in a plane parallel to the axis of rotation (longitudinalaxis) of the hollow fiber wound body 5, whereby the transport directionindicated by arrow 7 first proceeds obliquely to the axis of rotation ofthe hollow fiber wound body 5. Immediately before winding of the hollowfiber mat, the said mats are deflected so that the transport of thehollow fiber mats finally proceeds perpendicular to the axis of rotationof hollow fiber wound body 5. The deflection of the hollow fiber matsproceeds in the respective plane in such a way that the hollow fiberends on the one side of each hollow fiber mat describe a greater andthereby longer arc of a circle than the hollow fibers on the other sideof the hollow fiber mats. The hollow fiber ends which describe theouter, and thereby longer, arc of the circle lag behind the hollow fiberends which describe the inner, thus shorter, arc of the circle, so thatthe hollow fibers in this way are brought into an oblique positionrelative to the axis of rotation of the hollow fiber wound body 5,namely the oblique position of the hollow fibers of the one hollow fibermat is opposite to that of the hollow fibers of the other hollow fibermat. In this embodiment of the process as well, the oblique position ofthe hollow fibers can be changed by the degree of deflection of thehollow fiber mats, and a hollow fiber wound body can also be producedwith crossing but unidirectionally helically formed hollow fibers.

FIG. 9 shows different embodiments of hollow fiber mats A-F, which canbe combined according to the invention in any number, but at least two,and wound in a spiral form to produce the hollow fiber wound body. Theproduction of the depicted hollow fiber mats A-F can proceed accordingto the abovementioned processes but also according to processesaccording to the state of the art. An extensive description of thisprocess known per se for the production of hollow fiber mats isunnecessary. The axis of rotation of the hollow fiber wound body must bevisualized here as indicated, running perpendicular in the pictureplane, i.e., the transport of the hollow fiber mat proceeds in thepicture plane horizontally (longitudinal axis) of the hollow fiber woundbody. Each hollow fiber mat A-B consists of hollow fibers 1 and theinserted transverse fibers 2 or the like, with which they form the angleindicated in each case. Helical (in opposite directions) hollow fibersarise by (concurrent) winding of hollow fiber mats A and B. Rectilinearhollow fibers, running essentially parallel to the longitudinal axis ofthe hollow fiber wound body, arise by winding of hollow fiber mat C.Winding of hollow fiber mats D to F produces spiral hollow fibers, whichare disposed in planes that run essentially perpendicular to thelongitudinal axis of the hollow fiber wound body. Hollow fiber mats Dand E are hollow fiber mats in which the hollow fibers 1 are sealed onone side. The sealed end of hollow fibers 1 can be disposed along theexternal perimeter of the hollow fiber wound body or in the interior ofthe said body.

Example G in FIG. 9 is produced by a combination of hollow fiber mat A(hollow fibers 1a) and hollow fiber mat B (hollow fibers 1b). As will bedemonstrated below, there are numerous possibilities for combinationswithin the scope of the present invention, whereby it must only beconsidered that the hollow fibers of two adjacent hollow fiber mats orhollow fiber layers be disposed such that they cross. The winding, forexample, of a hollow fiber mat D and E or F with the depictedarrangement of hollow fibers 1 would therefore not be included withinthe invention.

The following combinations listed for the sake of illustration areregarded only as examples and not as limitations.

Possible combinations of hollow fiber mats A to F presented in FIG. 9:

A+B or C or D or E or F

A+B+C or D or E or F

A+B+A+B (optionally,+A+B, etc.)

A+B+C+A+B+C (optionally,+A+B+C, etc.)

B+C or D or E or F

C+D or E or F

C+D+C+E (optionally,+C+D+C+E, etc.)

The advantage of the embodiments shown in FIGS. 7 and 8 of the processfor the production of the hollow fiber wound body in particular is thefact that it is possible in this case to process hollow fiber matsimmediately after their production, e.g., on a loom or knitting machineinto a hollow fiber wound body, whereby the design of the hollow fibersin the hollow fiber wound body in so doing can be altered rapidly andsimply without interrupting the process.

FIG. 10 shows a device in which a hollow fiber wound body is disposed ina housing 8 with connections for fluid 9 and 10. The hollow fiber woundbody has hollow fibers 1a and 1b, the end regions of which arerespectively embedded in casting material slabs 11a and 11b, whereby thecasting material slabs 11a and 11b, respectively, are joined fluid-tightwith housing 8. The hollow fiber wound body in addition has the insertedtransverse fibers 2 or the like. The hollow fibers 1a or 1b,respectively, are porous, i.e., the sheath (wall) of hollow fibers 1a or1b, respectively, has open pores penetrating inwardly and outwardly, sothat a fluid or only a very specific fluid can pass through the pores.The end regions of the hollow fibers 1a and 1b, respectively, areembedded in casting material slabs 11a and 11b, respectively, such thathollow fibers 1a end at outer surface 12a of casting material block 11aand thus open into chamber 13, whereas their other ends are embedded incasting material slab 11b and thus are sealed. The situation isprecisely the opposite for hollow fibers 1b, i.e., hollow fibers 1b endat outer surface 12b of casting material slab 11b and thus open intochamber 14, whereas their other ends are embedded in casting materialslab 11a and thus are sealed. This device can thus be used as a type ofa two-stage dead-end filter (cascade filter) for filtration or foranother form of material separation. The pores of hollow fibers 1a canalso possess different pores for this purpose than the pores of hollowfibers 1b. Material separation, however, is also possible with hollowfiber membranes described as nonporous (so-called permeable).

If a fluid is allowed to flow, for example, through the connection forfluid 9 into hollow fibers 1a, then the fluid, the so-called filtrate orpermeate, separated totally or partially from some substance, entersthrough the sheath of hollow fibers 1a into extracapillary compartment15 and from there through the sheath (wall) of hollow fibers 1b,wherefrom the now twice filtered fluid again leaves the device throughchamber 14 and the connection for fluid 10, after another materialseparation has occurred by passage through the wall of hollow fibers 1b.

The hollow fiber wound body shown in FIG. 10 can be achieved, forexample, in that the hollow fiber mat(s) with hollow fibers 1a and thehollow fiber mat(s) with hollow fibers 1b are wound with mutual lateraldisplacement, so that the ends of hollow fibers 1a protrude on the oneside and the ends of hollow fibers 1b on the other side of the hollowfiber wound body. After embedding of the hollow fiber ends, for example,in a curable casting material, after curing of the casting material onlyso much of the two casting material slabs is removed that only hollowfibers 1a are exposed on the one side and only hollow fibers 1b on theother side, thus the said fibers open into cut surface 12a or 12b.

In the embodiment of the hollow fiber wound body as shown in FIG. 10,hollow fibers 1a are helical and hollow fibers 1b, in comparison withthese, helical in the opposite direction. As is evident from the above,this is only one of the possible designs for the hollow fibers and forthe hollow fiber wound body.

In another advantageous design, the hollow fiber wound body according toFIG. 10 can also contain solid or hollow fibers, which interactreactively with the fluid in the extracapillary compartment and thus,for example, effect a mass transfer from the fluid and/or into thefluid, a chemical and/or physical alteration of the fluid, or the like.Thus, for example, a blood plasma separation can be effected via poroushollow fibers 1a and plasma purification in the extracapillarycompartment, whereby the purified plasma can then again be removedthrough porous hollow fibers 1b. Fibers effecting a reaction with thefluid in the extracapillary compartment, however, can also be hollowfibers, for example, both ends of which are sealed, e.g., by castingmaterial slabs, and which are filled with a suitable substance.

FIG. 11 serves to illustrate the method to measure or determine thenovel ratios of the regular interval between adjacent transverse fibers2 within each hollow fiber mat to the regular interval between adjacenthollow fibers 1 within each hollow fiber mat. The regular intervalbetween adjacent transverse fibers 2 is designated with K_(j), and thatof the adjacent hollow fibers 1 with a_(i). The adjacent interval ineach case has the subscript j+1 or i+1, etc., up to j=m or i+n. Theregular intervals between transverse fibers 2 or hollow fibers 1 neednot be identical to each other, i.e., K_(j) need not be equal toK_(j+1), etc., and a_(i) need not be equal to a_(i+1), etc. Theintervals that belong together in each case, however, are included inthe determination of the interval ratio. Thus, the interval betweentransverse fibers 2 K_(j+1) and the regular interval between hollowfibers 1 in the region of transverse fibers 2, accordingly a_(i+1) here,are relevant for the calculation.

In the configuration shown in FIG. 11, transverse fibers 2 and hollowfibers 1 form a rectangle at the place of their smallest regularinterval, with the shorter side of the said rectangle being a_(i+1) longand the longer side K_(j+1) long. The interval ratio hereby thuscorresponds to the ratio of the side lengths of the respective rectangleformed by transverse fibers 2 and hollow fibers 1. The interval regionis to be measured differently according to the design, undulations,crimping, etc., of hollow fibers 1, as is possible by simple tests. Ifthe measurements within the novel region are correct, mutual contactbetween hollow fibers is avoided with certainty with typical hollowfibers suitable for heat and/or mass transfer.

The processing of the hollow fiber wound body into a usable unit, inwhich the hollow fiber ends are embedded in a casting material slab, canbe facilitated by sealing the open ends of the hollow fibers even in thewinding of the hollow fiber mats. This can be effected, for example, bywelding, by gluing, but particularly by squeezing. To achieve the lastmentioned type of sealing of hollow fiber ends, the ends of the hollowfibers of the hollow fiber mats are passed through squeeze rolls beforewinding, the said rolls which flatten the hollow fiber ends and therebypress them together so greatly that a permanent deformation or evenwelding of the sheath of the hollow fibers in this region and therebyclosure of the hollow fiber ends are achieved. The hollow fiber ends canalso be closed by tying with warp threads specifically introduced intothis region, or the like.

In the embedding or introduction of hollow fiber ends into a curablecasting material, such as for example polyurethane, silicone, or thelike, entry of the casting material into the lumen of the hollow fiberis prevented, whereas the entry of the casting material between thehollow fibers, thus into the extracapillary compartment, is promoted.Moreover, the sealing of the hollow fibers, being generally necessarybefore the embedding or introduction of the hollow fibers into thecasting material, for example by wax (so-called waxing) is herebyeconomically avoided.

The winding of the hollow fiber mats, as set forth above, can proceed ona core, which remains within the hollow fiber wound body. It is alsopossible, however, to use a core which is removed after the winding ofthe hollow fiber mats into a hollow fiber wound body.

In using hollow fiber mats, the hollow fibers of which form an anglewith the axis of rotation of the hollow fiber wound body, the beginningand/or the end of the hollow fiber mats can be cut parallel to the axisof rotation and the open hollow fibers arising thereby can be sealedthereafter or concurrently, for example, by so-called welding, in whichcutting and sealing of the hollow fiber ends occurs in a singleoperation. As a result, the beginning and/or the end of this hollowfiber mat runs parallel to the winding axis and is not formed as lobes.This can be very advantageous for handling the hollow fiber mats duringwinding into a hollow fiber wound body and also during unwinding of ahollow fiber wound body, and can facilitate handling. The unwindingoccurs, for example, when several smaller hollow fiber wound bodies orother hollow fiber structures are produced from a larger hollow fiberwound body.

The transverse fibers or the other means for keeping the hollow fibersat a regular interval from each other can also be formed by adhesivetape, particularly however by polyurethane cast fibers, which, forexample, are formed in that the polyurethane is applied in a pourablestate and if necessary between the hollow fibers and then left to cure.This can also occur immediately before the winding.

There is a great advantage, in addition, when the same material is usedfor the core of the hollow fiber wound body as for the embeddingmaterial, e.g., polyurethane, plasticized PVC, and the like. Thisfacilitates the cutting of ends or another form of removing a portion ofthe casting material to expose and open the hollow fiber ends.

The hollow fibers of the hollow fiber wound body can also be formed inthe shape of a U, and the hollow fiber ends accordingly are embedded onthe one side. This type of hollow fiber wound body can be used in theemployment of suitable hollow fibers, for example, as dead-end filters.It is also possible, however, in this case to permit each of the twoends of the hollow fibers to open into separate chambers and thus enablethe flow through the hollow fibers from one hollow fiber end to theother.

In using solid fibers, as set forth in detail above, these can beintroduced in addition to the hollow fibers or instead of individualhollow fibers as well, and can also be integrated into the hollow fibermats.

What is claimed is:
 1. A multilayer hollow fiber wound body, comprisingat least two superposed hollow fiber mats in the form of a wound bodycomprising a plurality of hollow fiber plies;said mats each comprisinghollow fibers and transverse fibers, said hollow fibers being held bysaid transverse fibers and at least one portion of the hollow fibersbeing formed as helices or spirals on said wound body; hollow fiberswithin each said mat being disposed at regular intervals and transversefibers within each said mat being disposed at regular intervals, a ratioof the regular interval between adjacent transverse fibers to theregular interval between adjacent hollow fibers defining a parallelogramwith said adjacent transverse fibers being in the range of 2 to 40;hollow fibers of a ply of said wound body being disposed so as to crosshollow fibers of an adjacent successive ply of said wound body; and noneof said hollow fibers having a deflection site.
 2. A hollow fiber woundbody according to claim 1, wherein all said hollow fibers are formed ashelices.
 3. A hollow fiber wound body according to claim 1, wherein thehollow fibers of at least one said mat are disposed helically in adirection opposite to a direction of other said hollow fibers of saidwound body.
 4. A hollow fiber wound body according to claim 1, whereinat least one of the hollow fibers and the transverse fibers arestructured or shaped.
 5. A hollow fiber wound body according to claim 1,wherein the hollow fibers of at least one said mat are disposed ingroups comprising inner hollow fibers and outer hollow fibers, whereinat least in selected regions the interval between adjacent hollow fiberswithin a group is smaller than the interval between the outer hollowfibers of adjacent hollow fiber groups.
 6. A hollow fiber wound bodyaccording to claim 1, wherein solid fibers are disposed in place of aportion of the hollow fibers.
 7. A hollow fiber wound body according toclaim 1, wherein the hollow fibers of different mats have differentproperties or functions.
 8. A hollow fiber wound body according to claim1, wherein the hollow fibers of different mats have different dimensionsrelative to at least one member of the group consisting of internalcontour, external contour, wall thickness and length.
 9. A hollow fiberwound body according to claim 1, wherein the hollow fibers of differentmats have a different cross sectional form.
 10. A hollow fiber woundbody according to claim 1, wherein the hollow fibers of at least one matare sealed at least at one end of said at least one mat.
 11. A hollowfiber wound body according to claim 1, wherein a fluid-permeable fabricis disposed between at least two plies of the wound body.